Children living in Appalachia rank lowest in the U.S. on indicators of oral health status. The substandard quality of oral health is consistent with well-documented findings that poor (and minority) children account for the majority of dental decay. We are applying a multidisciplinary approach to investigating factors contributing to this disparity. This application is a request for supplemental funding to extend the scope of our currently funded Genetics and Psychosocial Projects by addressing the microbiological contribution to poor oral health, particularly caries, in the same Appalachian sample. We will investigate the overall composition of oral flora in the total study population (1500 individuals in 250 families), and then intensely study Streptococcus mutans (S. mutans) in a subset of 50 people from the highest- and lowest-risk families. S. mutans is considered to be a principal or the principal cause of dental caries. S. mutans is quite diverse at the genetic level; multiple genotypes are isolated from children and their parents, and from young adults. More strains are isolated from those with caries (~5) than those without caries (~3). The overall goal of this study is to compare the genetic diversity and virulence characteristics of S. mutans strains from high caries and low caries families in order to gain insight into the extent that poor oral health can be attributed to host factors versus S. mutans characteristics. In addition, we will develop high throughput methods for genotyping and screening S. mutans that can be applied in future, larger studies. We will compare the genetic diversity and virulence characteristics of S. mutans isolated from the tongue, saliva and supra-gingival plaque of individuals from 5-6 high caries families to those from 5-6 low caries families, approximately 1000 isolates each from 50 individuals. We will use various laboratory techniques to do so, including arbitrarily primed PCR, PCR, and dot blot hybridization. The techniques will also allow us to determine the extent that S. mutans are shared between individuals within a family or community, and the extent that the strains vary over time. Study results will guide the development of more effective caries prevention strategies. [unreadable] [unreadable] LAY SUMMARY: Factors such as using fluoride products and toothbrushing decrease rates of dental decay, but some people who do so still have high rates of dental cavities. One cause of dental decay is bacteria found in the mouth, especially Streptococcus mutans. In this study we will compare the characteristics of S. mutans found in the mouth of families with high rates of dental cavities to that found in the mouth of those with low rates of dental cavities. This will help us understand how much of the differences in dental health is due to the S. mutans and to other factors. [unreadable] [unreadable] [unreadable]